Curry combines in a seamless way features from functional programming
(nested expressions, higher-order functions, lazy evaluation), logic
programming (logical variables, partial data structures, built-in search),
and concurrent programming (concurrent evaluation of expressions
with synchronization on logical variables).
Moreover, Curry provides additional features in comparison to the pure
languages (compared to functional programming: search, computing with partial
information; compared to logic programming: more efficient evaluation due
to the deterministic and demand-driven evaluation of functions).

The development of Curry is an international initiative intended to
provide a common platform for the research, teaching and application of
integrated functional logic languages. The design of Curry is mainly
discussed in the Curry mailing list.
A detailed report describing the language is available.
To get an idea of Curry, you may have a look into the short list of
Curry's features
or a tutorial on Curry.